Method and system for providing pulsed electrical stimulation to provide therapy for erectile/sexual dysfunction, prostatitis, prostatitis pain, and chronic pelvic pain

ABSTRACT

A method and system for providing pulse electrical stimulation to at least one of sacral plexus or its branches or portions, inferior hypogastric plexus or its branches or portions, superior hypogastric plexus or its branches or portions in a patient, to provide therapy for one of erectile/sexual dysfunction, prostatitis, pelvic pain, and pain originating from prostatitis pathology. The stimulation system comprises both implanted and external components. The pulsed electrical stimulation may be provided using one of the following stimulation systems: a) an implanted stimulus-receiver with an external stimulator; b) an implanted stimulus-receiver comprising a high value capacitor for storing charge, used in conjunction with an external stimulator; c) a programmer-less implantable pulse generator (IPG) which is operable with an external magnet; d) a programmable implantable pulse generator; e) a combination implantable device comprising both a stimulus-receiver and a programmable IPG; and f) an implantable pulse generator (IPG) comprising a rechargeable battery. The stimulation pulses can be provided uni-directionally. In one embodiment, the external components such as the programmer or external stimulator may comprise a telemetry means for networking. The telemetry means therefore, allows for interrogation or programming of implanted device from a remote location, over a wide area network.

FIELD OF INVENTION

The present invention relates to neurostimulation, more specificallyneurostimulation of selective nerves or nerve bundles to provide therapyfor erectile/sexual dysfunction, prostatitis, prostatitis pain, andchronic pelvic pain.

BACKGROUND

This disclosure is directed to pulsed electrical stimulation of nervesor nerve bundle in the sacral or pelvic region, or branches of suchnerves or portion thereof, to provide therapy for erectile/sexualdysfunction, prostatitis, pain originating from prostate pathology, andchronic pelvic pain. The method and system of this invention comprisesboth implantable and external components. The nerve stimulation may beto different nerves in the sacral and/or pelvic regions of the body. Toprovide therapy for erectile dysfunction, the selective neurostimulationis to cavernous nerve or pudendal nerve or its branches or portionthereof. To provide therapy for prostatitis or chronic pelvic pain, theselective neurostimulation is provided to one or more of the pudendalnerve or its branches or portion thereof, the prostatic plexus or itsbranches or portions thereof, or the sacral splanchnic nerve or itsbranches or portions thereof.

General anatomy of the sacral region is shown in conjunction withFIG. 1. The relation of sciatic nerves 24 and pudendal nerve 20 inrelation to sacral region is also shown in FIG. 1. There are five pairsof sacral nerves in the body. A more detailed anatomy of the five sacralnerves, their branches including the pudendal nerve is depicted in FIG.2.

FIG. 3 and FIG. 4 show more details of the relevant anatomy. The malesexual organ (FIG. 4) and the innervation to the penis via cavernousnerve 28 is shown in FIG. 3 in more detail. Despite the obviousstructural differences between the female and male reproductive organs,their neural regulation is surprisingly similar. Sexual arousal of adultmen and women can result from erotic psychological and sensory stimuli,and from direct tactile stimulation of the external sex organs. A fullsexual response cycle consists of arousal followed by plateau, orgasm,and resolution phases. Although the duration of each phase can varywidely, the physiological changes associated with each one arerelatively consistent. Neural control of the sexual response comes inpart from the cerebral cortex but the spinal cord coordinates this brainactivity with sensory information from the genitals and generates thecritical outputs that mediate the sexual responses of the genitalstructures.

The major external and internal sex organs are depicted in FIG. 5.Sexual arousal causes certain parts of the external genitals of bothwomen and men to become engorged with blood, and thus to swell. Inwomen, these structures include the labia and the clitoris; in men, itis primarily the penis. The external genitals are densely innervated bymechanoreceptors, particularly within the clitoris and the glans of thepenis. Adequate stimulation of these sensory endings can, by itself beenough to cause engorgement and erection. The evidence that engorgementcan be generated by a simple spinal reflex is that most men who havesuffered a complete transection of the spinal cord at the thoracic orlumbar level, can nevertheless generate an erection when their penis ismechanically stimulated. The mechanosensory pathways from the genitalsare components of the somatosensory system, and their anatomy followsthe usual pattern: Axons from mechanoreceptors in the penis and clitoriscollect in the dorsal roots of the sacral spinal cord (FIG. 5). Theythen send branches into the dorsal horns of the cord, and into thedorsal columns, through which they project toward the brain.

Engorgement and erection are controlled primarily be axons of theparasympathetic division of the autonomic nervous system (ANS). Withinthe sacral spinal cord, the parasympathetic neurons can be excited byeither mechanosensory activity from the genitals (which can directlytrigger reflexive erection), or by axons descending from the brain(which account for responses mediated by more cerebral stimuli).Engorgement of the clitoris and penis depend on dramatic changes inblood flow. Parasympathetic nerve endings are thought to release apotent combination of acetylcholine, vasoactive intestinal polypeptide(VIP), and nitric oxide (NO) directly into the erectile tissues. Theseneurotansmitters cause the relaxation of smooth muscle cells in thearteries and the spongy substance of the clitoris and penis. The usuallyflaccid arteries then become filled with blood, thereby distending theorgans. (Sildenafil, a drug with the trade name Viagra, is a treatmentfor erectile dysfunction that works by enhancing the effects of NO). Asthe penis becomes longer and thicker, the spongy internal tissues swellagainst two thick elastic outer covering of connective tissue that givethe erect penis its stiffness. In order to keep the organs slidingeasily during copulation throughout the plateau phase, parasympatheticactivity also stimulates the secretion of lubricating fluids from thewoman's vaginal wall and from the man's bulbourethral gland.

Completing the sexual response cycle requires activity from thesympathetic division of the autonomic nervous system (ANS). As sensoryaxons, particularly from the penis or clitoris, become highly active,they together with activity descending from the brain, excitesympathetic neurons in the thoracic and lumbar segments of the spinalcord. In men, the sympathetic efferent axons then trigger the process ofemission. Finally during ejaculation, a series of coordinated muscularcontractions expel the semen from the urethra, and this is usuallycoincident with the intense sensations of orgasm. In women, stimulationadequate to trigger orgasm probably also activates the sympatheticsystem. Sympathetic outflow causes the outer vaginal wall to thickenand, during orgasm itself, triggers a series of strong muscularcontractions. Following an orgasm, some time must pass before anotherorgasm can be triggered in men. The orgasmic experience of women tendsto be considerably more variable in frequency and intensity. Theresolution phase, which ends the sexual response cycle, includes adraining of blood from the external genitals through veins, and a lossof erection and other signs and sensations of sexual excitement.

Medical studies have shown that electrical stimulation of the cavernousnerve provides treatment for erectile dysfunction in humans. FIG. 6depicts the location of cavernous nerve 28 at a point convenient forplacing electrodes for neurostimulation. For implanting a system forerectile dysfunction, an incision is made for exposing the nerve tissue.As depicted in FIG. 7, the cavernous nerve 28 is exposed, and the distalportion of the lead is placed in the tissue, with electrodes in contactwith the nerve tissue to be stimulated. The terminal portion of the leadis tunneled subcutaneously to a site where the pulse generator means isimplanted, which is usually in the abdominal area. The tissues aresurgically closed in layers, and stimulation can be applied after thetissues are healed from the surgery.

In one aspect of the invention, the pulsed electrical stimulation isapplied to provide therapy for, or alleviating the symptoms ofprostatitus and chronic pelvic pain. For providing such therapy, theelectrodes are implanted on, or adjacent to one or more of the pudendalnerve or its branches or portions thereof, or the prostatic plexus orits branches or portions thereof, or the hypogastric nerve or itsbranches or portions thereof. Detailed anatomy of this region is shownin conjunction with FIGS. 8A, and 8B, 8C. The placement of electrodes toprovide such therapy is also shown in conjunction with FIGS. 8B and 8C,and can be at a convenient location on one or more sites of the sacral,inferior hypogastric or superior hypogastric plexus or their branches orportions thereof.

Pulsed electrical stimulation induces nerve impulses in the form ofaction potentials in the nerve fibers. Shown in conjunction with FIG. 9,the information in the nervous system is coded by frequency of firingrather than the size of the individual action potentials. The bottomportion of FIG. 9 shows a train of action potentials 7. Shown inconjunction with FIG. 10, the rate of action potential generationdepends on the magnitude of the depolarizing current. Thus, the firingfrequency of action potentials reflects the magnitude of thedepolarizing current. This is one way that stimulation intensity isencoded in the nervous system, as shown in FIG. 10. Although firingfrequency increases with the amount of depolarizing current, there is alimit to the rate at which neurons can generate action potentials,depending on the absolute refractory period and the relative refractoryperiod.

In the method and system of this invention, pulsed electricalstimulation is provided using both implanted and external components.The pulse generator may be implanted in the body, or may be external tothe body. In one aspect the external components may be networked over awide area network, for remote interrogation and remote programming ofstimulation parameters.

PRIOR ART

U.S. Patent Application No. 2004/0049240 A1 (Gerber et al.) is directedto electrical and/or magnetic stimulation therapy for providing painrelief to patients suffering from prostatitis, protatalgia, orprotatodynia.

U.S. Pat. No. 6,650,943 B1 (Whitehurst et al.) is generally directed tothe use of a leadless microstimulator to provide nerve stimulation as atherapy for erectile dysfunction and other sexual dysfunction. Themicrostimulator of this patent having a diameter of approximately 4 mmand having a length of approximately 20-30 mm.

U.S. Pat. No. 6,169,924 B1 (Meloy et al.) is generally directed tospinal cord stimulation to treat orgasmic dysfunction.

U.S. Patent Application No. 2004/0073268A1 (Zappala) mearly disclosesplacement of a lead via the dorsal vein of the phallus, for stimulationdevice for managing erectile dysfunction.

U.S. Pat. No. 5,938,584 (Ardito) is generally directed to stimulatingthe cavernous nerve with two pairs of bipolar leads and an implantedpulse generator.

U.S. Patent Application No. 2003/0236557 A1 (Whitehurst et al.) isgenerally directed to unidirectional propagation of action potentialswith cavernous nerve stimulation using microstimulators.

Other Publications

-   Shafik A., “Extrapelvic cavernous nerve stimulation in erectile    dysfunction. Human study, Andrologia 28, pp. 151-156 (1996).-   Lue T. F. et al., “Electrostimulation and penile erection”, Urol.    Int. 40: pp. 60-64 (1985).-   Martinez-Pineiro L. et al., “Rat model for the study of penile    erection, pharmacologic and electrical-stimulation parameters”, Eur.    urol. 25: pp. 62-70 (1994).-   Shafik A. et al., “Magnetic stimulation of the cavernous nerve for    the treatment of erectile dysfunction in humans”, Int. J. Impot.    Res. 12(3) pp. 137-142 (2000). [Based on abstract of the article]-   Shafik A. et al., “Perineal nerve stimulation: Role in penile    erection”, Int. J. Impot. Res. 9 pp. 11-16 (1997). [Based on    abstract of the article]

SUMMARY OF THE INVENTION

The present invention has certain objects. That is, various embodimentsof the present invention provide solution to one or more problemsexiting in the prior art, including the problems of: a) testing theeffectiveness of the therapy with a device and then implanting adifferent system to provide therapy; b) patient requires periodicsurgeries to replace systems at the end of battery-life, (typicalbattery life is 3-6 years); c) patient is not able to easily changebetween an implanted, external, or integrated system; d) patient isunable to make use of ‘cumulative effect’ of therapy to reduce/eliminateof disorders in addition to just ‘event’ based therapy due to limitedbattery life of exiting systems; e) frequent patients visits toclinics/physician office to monitor the device; f) titration of therapyis a long and drawn out.

The method and system of the current invention provides pulsedelectrical stimulation to provide therapy for erectile/sexualdysfunction and prostatitus/chronic pain. The stimulation is tocavernous nerve or its branches or portion thereof, to provide therapyfor erectile/sexual dysfunction. To provide therapy for prostatitischronic pelvic pain, the stimulation is to pudendal nerve or itsbranches or portion thereof, the prostatic plexus or its branches orportion thereof, or the sacral splanchnic nerve or its branches orportion thereof. The method and system comprises both implantable andexternal components. The power source may also be external or implantedin the body. The system to provide selective stimulation may be selectedfrom a group consisting of:

-   -   a) an implanted stimulus-receiver with an external stimulator;    -   b) an implanted stimulus-receiver comprising a high value        capacitor for storing charge, used in conjunction with an        external stimulator;    -   c) a programmer-less implantable pulse generator (IPG) which is        operable with a magnet;    -   d) a programmable implantable pulse generator (IPG);    -   e) a combination implantable device comprising both a        stimulus-receiver and a programmable IPG; and    -   f) an IPG comprising a rechargeable battery.

In one aspect of the invention, the selective stimulation site on one ormore of the sacral plexus or its branches, inferior hypogastric plexusor its branches, superior hypogastric plexus or its branches in apatient may be anywhere along the length of nerve fibers.

In another aspect of the invention, the stimulation may beunidirectional.

In another aspect of the invention, the external components such as theexternal stimulator or programmer comprise telemetry means adapted to benetworked, for remote interrogation or remote programming of the device.

In another aspect of the invention, the pulse generator may be implantedin the body.

In another aspect of the invention, the implanted pulse generator isadapted to be re-chargable via an external power source.

In another aspect of the invention, the implanted lead body may be madeof a material selected from the group consisting of polyurethane,silicone, and silicone with polytetrafluoroethylene.

In another aspect of the invention, the implanted lead comprises atleast one electrode selected from the group consisting of platinum,platinum/iridium alloy, platinum/iridium alloy coated with titaniumnitride, and carbon.

In yet another aspect of the invention, the implanted lead comprises atleast one electrode selected from the group consisting of spiralelectrodes, cuff electrodes, steroid eluting electrodes, wrap-aroundelectrodes, and hydrogel electrodes.

Various other features, objects and advantages of the invention will bemade apparent from the following description taken together with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there are shown inaccompanying drawing forms which are presently preferred, it beingunderstood that the invention is not intended to be limited to theprecise arrangement and instrumentalities shown.

FIG. 1 is a diagram depicting five pairs of sacral nerves.

FIG. 2 is a diagram depicting branches of sacral nerves.

FIG. 3 is a diagram depicting innervation of the cavernous nerves.

FIG. 4 is a diagram showing the anatomy of the penis.

FIG. 5 is a diagram depicting innervation of male and female sexualorgans.

FIG. 6 is a diagram showing the course of the cavernous nerve.

FIG. 7 is a diagram showing a site for incision, to expose the cavernousnerve.

FIGS. 8A-8C show detailed anatomy of the nerves in the sacral and pelvicregions.

FIG. 9 is an illustration showing a train of action potentials.

FIG. 10 is a diagram depicting action potentials in response to changingdepolarization currents.

FIG. 11 is a simplified block diagram depicting supplying amplitude andpulse width modulated electromagnetic pulses to an implanted coil.

FIG. 12 shows coupling of the external stimulator and the implantedstimulus-receiver.

FIG. 13 is a schematic of the passive circuitry in the implantedlead-receiver.

FIG. 14A is a schematic of an alternative embodiment of the implantedlead-receiver.

FIG. 14B is another alternative embodiment of the implantedlead-receiver.

FIG. 15 is a top-level block diagram of the external stimulator andproximity sensing mechanism.

FIG. 16 is a diagram showing the proximity sensor circuitry.

FIG. 17 shows the pulse train to be transmitted to the nerve tissue.

FIG. 18 shows the ramp-up and ramp-down characteristic of the pulsetrain.

FIG. 19 is a schematic diagram of the implantable lead.

FIGS. 20A, 20B, and 20C depicts various types of electrodes at thedistal end of a lead.

FIGS. 21A, 21B, 21C, 21D, and 21E are diagrams depicting various typesof anchoring sleeves.

FIG. 22A is diagram depicting stimulating electrode-tissue interface.

FIG. 22B is diagram depicting an electrical model of theelectrode-tissue interface.

FIG. 23 is a schematic diagram showing the implantable lead and one formof stimulus-receiver.

FIG. 24 is a schematic block diagram showing a system forneuromodulation of nerve tissue, with an implanted component which isboth RF coupled and contains a capacitor power source.

FIG. 25 is a simplified block diagram showing control of an implantableneurostimulator with a magnet.

FIG. 26 is a schematic diagram showing implementation of a multi-stateconverter.

FIG. 27 is a schematic diagram depicting digital circuitry for statemachine.

FIG. 28 is a simplified block diagram of the implantable pulsegenerator.

FIG. 29 is a functional block diagram of a microprocessor-basedimplantable pulse generator.

FIG. 30 shows details of implanted pulse generator.

FIGS. 31A and 31B show details of digital components of the implantablecircuitry.

FIG. 32A shows a schematic diagram of the register file, timers andROM/RAM.

FIG. 32B shows datapath and control of custom-designed microprocessorbased pulse generator.

FIG. 33 is a block diagram for generation of a pre-determinedstimulation pulse.

FIG. 34 is a simplified schematic for delivering stimulation pulses.

FIG. 35 is a circuit diagram of a voltage doubler.

FIG. 36 is a diagram depicting ramping-up of a pulse train.

FIG. 37 depicts an implantable system with tripolar lead for selectiveunidirectional blocking of nerve stimulation FIG. 38 is a diagramshowing different types of nerve fibers and their properties.

FIG. 39 depicts selective unidirectional blocking with nervestimulation.

FIGS. 40A and 40B are diagrams showing communication of programmer withthe implanted stimulator.

FIGS. 41A and 41B show diagrammatically encoding and decoding ofprogramming pulses.

FIG. 42 is a simplified overall block diagram of implanted pulsegenerator (IPG) programmer.

FIG. 43 shows a programmer head positioning circuit.

FIG. 44 depicts typical encoding and modulation of programming messages.

FIG. 45 shows decoding bits of signals.

FIG. 46 shows a diagram of receiving and decoding circuitry forprogramming data.

FIG. 47 shows a diagram of receiving and decoding circuitry fortelemetry data.

FIG. 48 is a block diagram of a battery status test circuit.

FIG. 49 is a diagram showing the two modules of the implanted pulsegenerator (IPG).

FIG. 50 is a schematic and functional block diagram showing thecomponents and their relationships to the implantable pulsegenerator/stimulus-receiver.

FIGS. 51A, 51B and 51C show output pulses from a comparator when inputexceeds a reference voltage.

FIGS. 52A and 52B are simplified block diagrams showing the switchingrelationships between the inductively coupled and battery poweredassemblies of the pulse generator.

FIG. 53 shows a picture of the combination implantable stimulator.

FIG. 54 shows assembly features of the implantable portion of thesystem.

FIG. 55 depicts an embodiment where the implantable system is used as animplantable, rechargeable system.

FIG. 56 depicts remote monitoring of stimulation devices.

FIG. 57 is an overall schematic diagram of the external stimulator,showing wireless communication.

FIG. 58 is a schematic diagram showing application of WirelessApplication Protocol (WAP).

FIG. 59 is a simplified block diagram of the networking interface board.

FIGS. 60A and 60B are simplified diagrams showing communication ofmodified PDA/phone with an external stimulator via a cellular tower/basestation.

DETAILED DESCRIPTION OF THE INVENTION

The method and system of the current invention delivers pulsedelectrical stimulation, to provide therapy for erectile/sexualdysfunction and prostatitus/chronic pelvic pain. The electricalstimulation is delivered to one or more of the cavernous (or pudendal)nerve(s) to provide therapy for erectile/sexual dysfunction. To providetherapy for prostatitis/chronic pelvic pain, the electrical stimulationis delivered to one or more of the pudendal nerve or its branches, theprostatic plexus or its branches, or the sacral splanchnic nerve or itsbranches. The method and system comprises both implantable and externalcomponents.

For implantation of the system, an incision is made for exposing thenerve tissue to be stimulated, and the distal portion of the lead isimplanted in the tissue with electrodes in contact with the nerve tissueto be stimulated. The terminal portion of the lead is tunneledsubcutaneously to a site where the pulse generator means is implanted,which is usually in the abdominal area. The pulse generator means isconnected to the proximal end 44 of the lead, placed in a subcutaneouspocket, and the tissues are surgically closed in layers. Stimulationtherapy can be applied after the tissues are healed from the surgery.

In the method and system of this invention, the pulse generator meansmay be implanted in the body or may be external to the body. Also, thepower source may be external, implantable, or a combination device.

In the method of this invention, a simple and cheap pulse generator maybe used to test a patient's response to neuromodulation therapy. As oneexample only, an implanted stimulus-receiver in conjunction with anexternal stimulator may be used initially to test patient's response. Ifthe patient responds well, then at a later time, the pulse generator maybe exchanged for a more elaborate implanted pulse generator (IPG) model,keeping the same lead. Some examples of stimulation and power sourcesthat may be used interchangeably with the same lead for the practice ofthis invention, and disclosed in this Application, include:

-   -   a) an implanted stimulus-receiver with an external stimulator;    -   b) an implanted stimulus-receiver comprising a high value        capacitor for storing charge, used in conjunction with an        external stimulator;    -   c) a programmer-less implantable pulse generator (IPG) which is        operable with a magnet;    -   d) a programmable implantable pulse generator (IPG);    -   e) a combination implantable device comprising both a        stimulus-receiver and a programmable IPG; and    -   f) an IPG comprising a rechargeable battery.

As another example, a cheap programmer-less IPG may be implantedinitially to test the efficacy of neuromodulation therapy in thepatient. If the patient responds well, the simple programmer-less IPGmay be replaced with a higher functionality (and more expensive) versionof IPG at a future time.

Also as disclosed later, the external components such as a programmer,or external pulse generator, may comprise a telemetry module for remotecommunication over the internet. This would provide means of remotelyinterrogating the device, or loading or activating new programs from aremote location.

Even though the pulse generator means are interchangeble, the lead isimplanted only once. The proximal (or terminal) portion of the lead isplugged into the pulse generator means. The distal portion of the leadcomprises two, or three, or four electrodes for delivering electricalstimulation. As described earlier in the background, the pulsedelectrical stimulation may be to one of several nerves e.g. thecavernous nerve, the pudendal nerve etc. For the purpose of describingthe system, the stimulation site is referred to as simply “nerve tissue54”. It is to be understood that the nerve tissue 54 refers to theappropriate nerve or nerve plexus, or branches to be stimulated for theparticular therapy to be delivered.

Implanted Stimulus-Receiver with an External Stimulator

For an external power source, a passive implanted stimulus-receiver maybe used. The appropriate stimulation of selected nerve fibers in thesacral and pelvic region, as performed by one embodiment of the methodand system of this invention is shown schematically in FIG. 11, as ablock diagram. A modulator 246 receives analog (sine wave) highfrequency “carrier” signal and modulating signal. The modulating signalcan be multilevel digital, binary, or even an analog signal. In thisembodiment, mostly multilevel digital type i.e., pulse amplitude andpulse width modulated signals are used. The modulated signal isamplified 250, 252, conditioned 254, and transmitted via a primary coil46 which is external to the body. Shown in conjunction with FIG. 12, asecondary coil 48 of an implanted stimulus-receiver, receives,demodulates, and delivers these pulses to the nerve tissue 54 viaelectrodes 61 and 62 (or a proximal pair). The receiver circuitry 256 isdescribed later.

The carrier frequency is optimized. One preferred embodiment utilizeselectrical signals of around 1 Mega-Hertz, even though other frequenciescan be used. Low frequencies are generally not suitable because ofenergy requirements for longer wavelengths, whereas higher frequenciesare absorbed by the tissues and are converted to heat, which againresults in power losses.

Also, shown in conjunction with FIG. 12, the primary (external) coil 46of the external stimulator 42 is inductively coupled to the secondary(implanted) coil 48 of the implanted stimulus-receiver 34. Theimplantable stimulus-receiver has circuitry at the proximal end, and hasstimulating electrodes at the distal end of the lead.

The circuitry contained in the proximal end of the implantablestimulus-receiver 34 is shown schematically in FIG. 13, for oneembodiment. In this embodiment, the circuit uses all passive components.Approximately 25 turn copper wire of 30 gauge, or comparable thickness,is used for the primary coil 46 and secondary coil 48. This wire isconcentrically wound with the windings all in one plane. The frequencyof the pulse-waveform delivered to the implanted coil 48 can vary, andso a variable capacitor 152 provides ability to tune secondary implantedcircuit 167 to the signal from the primary coil 46. The pulse signalfrom secondary (implanted) coil 48 is rectified by the diode bridge 154and frequency reduction obtained by capacitor 158 and resistor 164. Thelast component in line is capacitor 166, used for isolating the outputsignal from the electrode wire. The return path of signal from cathode61 will be through anode 62 placed in proximity to the cathode 61 for“Bipolar” stimulation. In this embodiment bipolar mode of stimulation isused, however, the return path can be connected to the remote groundconnection (case) of implantable circuit 167, providing for much largerintermediate tissue for “Unipolar” stimulation. The “Bipolar”stimulation offers localized stimulation of tissue compared to“Unipolar” stimulation and is therefore, preferred in this embodiment.Unipolar stimulation is more likely to stimulate skeletal muscle inaddition to nerve stimulation. The implanted circuit 167 in thisembodiment is passive, so a battery does not have to be implanted.

The circuitry shown in FIGS. 14A and 14B can be used as an alternativefor the implanted stimulus-receiver. The circuitry of FIG. 14A is aslightly simpler version, and circuitry of FIG. 14B contains aconventional NPN transistor 168 connected in an emitter-followerconfiguration.

For therapy to commence, the primary (external) coil 46 is placed on theskin 60 on top of the surgically implanted (secondary) coil 48. Anadhesive tape may be placed on the skin 60 and external coil 46 suchthat the external coil 46, is taped to the skin 60. For efficient energytransfer to occur, it is important that the primary (external) andsecondary (internal) coils 46,48 be positioned along the same axis andbe optimally positioned relative to each other. In this embodiment, theexternal coil 46 may be connected to proximity sensing circuitry 50. Thecorrect positioning of the external coil 46 with respect to the internalcoil 48 is indicated by turning “on” of a light emitting diode (LED) onthe external stimulator 42.

Optimal placement of the external (primary) coil 46 is done with the aidof proximity sensing circuitry incorporated in the system, in thisembodiment. Proximity sensing occurs utilizing a combination of externaland implantable components. The implanted components contains arelatively small magnet composed of materials that exhibit GiantMagneto-Resistor (GMR) characteristics such as Samarium-cobalt, a coil,and passive circuitry. As was shown in conjunction with FIG. 12, theexternal coil 46 and proximity sensor circuitry 50 are rigidly connectedin a convenient enclosure which is attached externally on the skin. Thesensors measure the direction of the field applied from the magnet tosensors within a specific range of field strength magnitude. The dualsensors exhibit accurate sensing under relatively large separationbetween the sensor and the target magnet. As the external coil 46placement is “fine tuned”, the condition where the external (primary)coil 46 comes in optimal position, i.e. is located adjacent and parallelto the subcutaneous (secondary) coil 48, along its axis, is recorded andindicated by a light emitting diode (LED) on the external stimulator 42.

FIG. 15 shows an overall block diagram of the components of the externalstimulator and the proximity sensing mechanism. The proximity sensingcomponents are the primary (external) coil 46, supercutaneous (external)proximity sensors 648, 652 (FIG. 16) in the proximity sensor circuitunit 50, and a subcutaneous secondary coil 48 with a Giant MagnetoResister (GMR) magnet 53 associated with the proximity sensor unit. Theproximity sensor circuit 50 provides a measure of the position of thesecondary implanted coil 48. The signal output from proximity sensorcircuit 50 is derived from the relative location of the primary andsecondary coils 46, 48. The sub-assemblies consist of the coil and theassociated electronic components, that are rigidly connected to thecoil.

The proximity sensors (external) contained in the proximity sensorcircuit 50 detect the presence of a GMR magnet 53, composed of SamariumCobalt, that is rigidly attached to the implanted secondary coil 48. Theproximity sensors, are mounted externally as a rigid assembly and sensethe actual separation between the coils, also known as the proximitydistance. In the event that the distance exceeds the system limit, thesignal drops off and an alarm sounds to indicate failure of theproduction of adequate signal in the secondary implanted circuit 167, asapplied in this embodiment of the device. This signal is provided to thelocation indicator LED 280.

FIG. 16 shows the circuit used to drive the proximity sensors 648, 652of the proximity sensor circuit 50. The two proximity sensors 648, 652obtain a proximity signal based on their position with respect to theimplanted GMR magnet 53. This circuit also provides temperaturecompensation. The sensors 648, 652 are ‘Giant Magneto Resistor’ (GMR)type sensors packaged as proximity sensor unit 50. There are twocomponents of the complete proximity sensor circuit. One component ismounted supercutaneously 50, and the other component, the proximitysensor signal control unit 57 is within the external stimulator 42. Theresistance effect depends on the combination of the soft magnetic layerof magnet 53, where the change of direction of magnetization fromexternal source can be large, and the hard magnetic layer, where thedirection of magnetization remains unchanged. The resistance of thissensor 50 varies along a straight motion through the curvature of themagnetic field. A bridge differential voltage is suitably amplified andused as the proximity signal.

The Siemens GMR B6 (Siemens Corp., Special Components Inc., New Jersey)is used for this function in one embodiment. The maximum value of thepeak-to-peak signal is observed as the external magnetic field becomesstrong enough, at which point the resistance increases, resulting in theincrease of the field-angle between the soft magnetic and hard magneticmaterial. The bridge voltage also increases. In this application, thetwo sensors 648, 652 are oriented orthogonal to each other.

The distance between the magnet 53 and sensor 50 is not relevant as longas the magnetic field is between 5 and 15 KA/m, and provides a range ofdistances between the sensors 648, 652 and the magnetic material 53. TheGMR sensor registers the direction of the external magnetic field. Atypical magnet to induce permanent magnetic field is approximately 15 by8 by 5 mm³, for this application and these components. The sensors 648,652 are sensitive to temperature, such that the corresponding resistancedrops as temperature increases. This effect is quite minimal until about100° C. A full bridge circuit is used for temperature compensation, asshown in temperature compensation circuit 50 of FIG. 16. The sensors648, 652 and a pair of resistors 650, 654 are shown as part of thebridge network for temperature compensation. It is also possible to usea full bridge network of two additional sensors in place of theresistors 650, 654.

The signal from either proximity sensor 648, 652 is rectangular if thesurface of the magnetic material is normal to the sensor and is radialto the axis of a circular GMR device. This indicates a shearing motionbetween the sensor and the magnetic device. When the sensor is parallelto the vertical axis of this device, there is a fall off of therelatively constant signal at about 25 mm. separation. The GMR sensorcombination varies its resistance according to the direction of theexternal magnetic field, thereby providing an absolute angle sensor. Theposition of the GMR magnet can be registered at any angle from 0 to 360degrees.

In the external stimulator 42 shown in FIG. 15, an indicator unit 280which is provided to indicate proximity distance or coil proximityfailure (for situations where the patch containing the external coil 46,has been removed, or is twisted abnormally etc.). Indication is alsoprovided to assist in the placement of the patch. In case of generalfailure, a red light with audible signal is provided when the signal isnot reaching the subcutaneous circuit. The indicator unit 280 alsodisplays low battery status. The information on the low battery, normaland out of power conditions forewarns the user of the requirements ofany corrective actions.

Also shown in FIG. 15, the programmable parameters are stored in aprogrammable logic 264. The predetermined programs stored in theexternal stimulator are capable of being modified through the use of aseparate programming station 77. The Programmable Array Logic Unit 264and interface unit 270 are interfaced to the programming station 77. Theprogramming station 77 can be used to load new programs, change theexisting predetermined programs or the program parameters for variousstimulation programs. The programming station is connected to theprogrammable array unit 75 (comprising programmable array logic 304 andinterface unit 270) with an RS232-C serial connection. The main purposeof the serial line interface is to provide an RS232-C standardinterface.

This method enables any portable computer with a serial interface tocommunicate and program the parameters for storing the various programs.The serial communication interface receives the serial data, buffersthis data and converts it to a 16 bit parallel data. The programmablearray logic 264 component of programmable array unit receives theparallel data bus and stores or modifies the data into a random accessmatrix. This array of data also contains special logic and instructionsalong with the actual data. These special instructions also provide analgorithm for storing, updating and retrieving the parameters fromlong-term memory. The programmable logic array unit 264, interfaces withlong term memory to store the predetermined programs. All the previouslymodified programs can be stored here for access at any time, as well as,additional programs can be locked out for the patient. The programsconsist of specific parameters and each unique program will be storedsequentially in long-term memory. A battery unit is present to providepower to all the components. The logic for the storage and decoding isstored in a random addressable storage matrix (RASM).

Conventional microprocessor and integrated circuits are used for thelogic, control and timing circuits. Conventional bipolar transistors areused in radio-frequency oscillator, pulse amplitude ramp control andpower amplifier. A standard voltage regulator is used in low-voltagedetector. The hardware and software to deliver the pre-determinedprograms is well known to those skilled in the art.

The pulses delivered to the nerve tissue for stimulation therapy areshown graphically in FIG. 17. As shown in FIG. 18, for patient comfortwhen the electrical stimulation is turned on, the electrical stimulationis ramped up and ramped down, instead of abrupt delivery of electricalpulses.

The selective stimulation to the nerve tissue can be performed in one oftwo ways. One method is to activate one of several “pre-determined”programs. A second method is to “custom” program the electricalparameters which can be selectively programmed, for specific therapy tothe individual patient. The electrical parameters which can beindividually programmed, include variables such as pulse amplitude,pulse width, frequency of stimulation, stimulation on-time, andstimulation off-time. Table two below defines the approximate range ofparameters, TABLE 2 Electrical parameter range delivered to the nervePARAMER RANGE Pulse Amplitude 0.1 Volt-10 Volts Pulse width 20 μS-5mSec. Frequency 5 Hz-200 Hz On-time 10 Secs-24 hours Off-time 10 Secs-24hours

The parameters in Table 2 are the electrical signals delivered to thenerve via the two electrodes 61,62 (distal and proximal) around thenerve, as shown in FIG. 18. It being understood that the signalsgenerated by the external pulse generator 42 and transmitted via theprimary coil 46 are larger, because the attenuation factor between theprimary coil and secondary coil is approximately 10-20 times, dependingupon the distance, and orientation between the two coils. Accordingly,the range of transmitted signals of the external pulse generator areapproximately 10-20 times larger than shown in Table 2.

Referring now to FIG. 19, the implanted lead component of the system issomewhat similar to cardiac pacemaker leads, except for distal portion40 (or electrode end) of the lead. The lead terminal preferably islinear, even though it can be bifurcated, and plug(s) into the cavity ofthe pulse generator means. The lead body 59 insulation may beconstructed of medical grade silicone, silicone reinforced withpolytetrafluoro-ethylene (PTFE), or polyurethane. The electrodes61,62,63,64 for stimulating the nerve tissue 54 may either wrap aroundthe nerve tissue or may be implanted adjacent to the nerve tissue to bestimulated.

FIGS. 20A, 20B, 20C show different types of electrodes at the distal end40 of the lead. FIG. 20A is a close up of electrodes 61,62,63,64 as wasshown in FIG. 19, with an anchoring sleeve 15 pulled back from the mostproximal electrode. FIG. 20B shows a paddle electrode. And FIG. 20Cshows a type of electrodes that can be wrapped around the nerve tissue54 to be stimulated.

In any of these leads, there may be one, or two, or three, or four, ormore electrodes. This provides flexibility in choosing a different pairto stimulate over the implanted life of the lead. FIGS. 21A, 21B, 21C,21D, and 21E show different types of anchoring devices (15,15A 15B,15C)used in the method and system of this invention. All anchoring devicesare make of silicone in this embodiment, even though they can be made ofother bicompatible material. FIGS. 21A, 21B, and 21C show anchoringsleeves which have holes for suturing the lead to the tissue. FIG. 21Dshows a type of suture sleeve that has grooves 15B for suturing to thetissue. FIG. 21E shows a passive fixation anchoring sleeve 15C where theholes in the silicone material promote tissue in-growth over time, forlead fixation.

The stimulating electrodes may be made of pure platinum,platinum/Iridium alloy or platinum/iridium coated with titanium nitride.The conductor connecting the terminal to the electrodes 61,62,63,64 ismade of an alloy of nickel-cobalt. The implanted lead design variablesare also summarized in table three below. TABLE 3 Lead design variablesProximal Distal End End Conductor (connecting Lead body- proximal LeadInsulation and distal Electrode - Electrode - Terminal MaterialsLead-Coating ends) Material Type Linear Polyurethane Antimicrobial Alloyof Pure Wrap-around bipolar coating Nickel- Platinum electrode CobaltBifurcated Silicone Anti- Platinum- Standard Ball Inflammatory Iridiumand Ring coating (Pt/Ir) Alloy electrodes Silicone with Lubricious Pt/Ircoated Steroid Polytetrafluoroethylene coating with Titanium eluting(PTFE) Nitride Carbon Hydrogel electrodes Cuff electrodes

Once the lead is fabricated, coating such as anti-microbial,anti-inflammatory, or lubricious coating may be applied to the body ofthe lead.

FIG. 22A summarizes electrode-tissue interface between the nerve tissueand electrodes 61, 62. There is a thin layer of fibrotic tissue betweenthe stimulating electrode 61 and the excitable nerve fibers of the nervetissue 54. FIG. 22B summarizes the most important properties of themetal/tissue phase boundary in an equivalent circuit diagram. Both themembrane of the nerve fibers and the electrode surface are representedby parallel capacitance and resistance. Application of a constantbattery voltage Vbat from the pulse generator, produces voltage changesand current flow, the time course of which is crucially determined bythe capacitive components in the equivalent circuit diagram. During thepulse, the capacitors Co, Ch and Cm are charged through the ohmicresistances, and when the voltage Vbat is turned off, the capacitorsdischarge with current flow on the opposite direction.

Implanted Stimulus-Receiver Comprising a High Value Capacitor forStoring Charge, Used in Conjunction with an External Stimulator

In one embodiment, the implanted stimulus-receiver may be a system whichis RF coupled combined with a power source. In this embodiment, theimplanted stimulus-receiver contains high value, small sizedcapacitor(s) for storing charge and delivering electric stimulationpulses for up to several hours by itself, once the capacitors arecharged. The packaging is shown in FIG. 23. Using mostly hybridcomponents and appropriate packaging, the implanted portion of thesystem described below is conducive to miniaturization. As shown in FIG.23, a solenoid coil 382 wrapped around a ferrite core 380 is used as thesecondary of an air-gap transformer for receiving power and data to theimplanted device. The primary coil is external to the body. Since thecoupling between the external transmitter coil and receiver coil 382 maybe weak, a high-efficiency transmitter/amplifier is used in order tosupply enough power to the receiver coil 382. Class-D or Class-E poweramplifiers may be used for this purpose. The coil for the externaltransmitter (primary coil) may be placed in the pocket of a customizedgarment.

As shown in conjunction with FIG. 24 of the implanted stimulus-receiver490 and the system, the receiving inductor 48A and tuning capacitor 403are tuned to the frequency of the transmitter. The diode 408 rectifiesthe AC signals, and a small sized capacitor 406 is utilized forsmoothing the input voltage V_(I) fed into the voltage regulator 402.The output voltage V_(D) of regulator 402 is applied to capacitiveenergy power supply and source 400 which establishes source powerV_(DD). Capacitor 400 is a big value, small sized capacative energysource which is classified as low internal impedance, low power loss andhigh charge rate capacitor, such as Panasonic Model No. 641.

The refresh-recharge transmitter unit 460 includes a primary battery426, an ON/Off switch 427, a transmitter electronic module 442, an RFinductor power coil 46A, a modulator/demodulator 420 and an antenna 422.

When the ON/OFF switch is on, the primary coil 46A is placed in closeproximity to skin 60 and secondary coil 48A of the implanted stimulator490. The inductor coil 46A emits RF waves establishing EMF wave frontswhich are received by secondary inductor 48A. Further, transmitterelectronic module 442 sends out command signals which are converted bymodulator/demodulator decoder 420 and sent via antenna 422 to antenna418 in the implanted stimulator 490. These received command signals aredemodulated by decoder 416 and replied and responded to, based on aprogram in memory 414 (matched against a “command table” in the memory).Memory 414 then activates the proper controls and the inductor receivercoil 48A accepts the RF coupled power from inductor 46A.

The RF coupled power, which is alternating or AC in nature, is convertedby the rectifier 408 into a high DC voltage. Small value capacitor 406operates to filter and level this high DC voltage at a certain level.Voltage regulator 402 converts the high DC voltage to a lower precise DCvoltage while capacitive power source 400 refreshes and replenishes.

When the voltage in capacative source 400 reaches a predetermined level(that is VDD reaches a certain predetermined high level), the highthreshold comparator 430 fires and stimulating electronic module 412sends an appropriate command signal to modulator/decoder 416.Modulator/decoder 416 then sends an appropriate “fully charged” signalindicating that capacitive power source 400 is fully charged, isreceived by antenna 422 in the refresh-recharge transmitter unit 460.

In one mode of operation, the patient may start or stop stimulation bywaving the magnet 442 once near the implant. The magnet emits a magneticforce Lm which pulls reed switch 410 closed. Upon closure of reed switch410, stimulating electronic module 412 in conjunction with memory 414begins the delivery (or cessation as the case may be) of controlledelectronic stimulation pulses to the nerve tissue 54 via a pair ofelectrodes. In another mode (AUTO), the stimulation is automaticallydelivered to the implanted lead based upon programmed ON/OFF times.

The programmer unit 450 includes keyboard 432, programming circuit 438,rechargeable battery 436, and display 434. The physician or medicaltechnician programs programming unit 450 via keyboard 432. This programregarding the frequency, pulse width, modulation program, ON time etc.is stored in programming circuit 438. The programming unit 450 must beplaced relatively close to the implanted stimulator 490 in order totransfer the commands and programming information from antenna 440 toantenna 418. Upon receipt of this programming data,modulator/demodulator and decoder 416 decodes and conditions thesesignals, and the digital programming information is captured by memory414. This digital programming information is further processed bystimulating electronic module 412. In the DEMAND operating mode, afterprogramming the implanted stimulator, the patient turns ON and OFF theimplanted stimulator via hand held magnet 442 and the reed switch 410.In the automatic mode (AUTO), the implanted stimulator turns ON and OFFautomatically according to the programmed values for the ON and OFFtimes.

Other simplified versions of such a system may also be used. Forexample, a system such as this, where a separate programmer iseliminated, and simplified programming is performed with a magnet andreed switch, can also be used.

Programmer-Less Implantable Pulse Generator (IPG)

In one embodiment, a programmer-less implantable pulse generator (IPG)may be used. In this embodiment, shown in conjunction with FIG. 25, theimplantable pulse generator 171 is provided with a reed switch 92 andmemory circuitry 102. The reed switch 92 being remotely actuable bymeans of a magnet 90 brought into proximity of the pulse generator 171,in accordance with common practice in the art. In this embodiment, thereed switch 92 is coupled to a multi-state converter/timer circuit 96,such that a single short closure of the reed switch can be used as ameans for non-invasive encoding and programming of the pulse generator171 parameters.

In one embodiment, shown in conjunction with FIG. 26, the closing of thereed switch 92 triggers a counter. The magnet 90 and timer are ANDedtogether. The system is configured such that during the time that themagnet 82 is held over the pulse generator 171, the output level goesfrom LOW stimulation state to the next higher stimulation state every 5seconds. Once the magnet 82 is removed, regardless of the state ofstimulation, an application of the magnet, without holding it over thepulse generator 171, triggers the OFF state, which also resets thecounter.

Once the prepackaged/predetermined logic state is activated by the logicand control circuit 102, as shown in FIG. 25, the pulse generation andamplification circuit 106 deliver the appropriate electrical pulses tothe nerve tissue 54 of the patient via an output buffer 108. Thedelivery of output pulses is configured such that the distal electrode61 is the cathode and the proximal electrode 62 is the anode. Timingsignals for the logic and control circuit 102 of the pulse generator 171are provided by a crystal oscillator 104. The battery 86 of the pulsegenerator 171 has terminals connected to the input of a voltageregulator 94. The regulator 94 smoothes the battery output and suppliespower to the internal components of the pulse generator 171. Amicroprocessor 100 controls the program parameters of the device, suchas the voltage, pulse width, frequency of pulses, on-time and off-time.The microprocessor may be a commercially available, general purposemicroprocessor or microcontroller, or may be a custom integrated circuitdevice augmented by standard RAM/ROM components.

In one embodiment, there are four stimulation states. A larger (orlower) number of states can be achieved using the same methodology, andsuch is considered within the scope of the invention. These four statesare, LOW stimulation state, LOW-MED stimulation state, MED stimulationstate, and HIGH stimulation state. Examples of stimulation parameters(delivered to the nerve tissue) for each state are as follows,

LOW stimulation state example is, Current output: 0.75 milliAmps. Pulsewidth: 0.20 msec. Pulse frequency: 40 Hz ON for 5 minutes

LOW-MED stimulation state example is, Current output: 1.5 milliAmps,Pulse width: 0.30 msec. Pulse frequency: 45 Hz ON for 7.5 minutes

MED stimulation state example is, Current output: 2.0 milliAmps. Pulsewidth: 0.40 msec. Pulse frequency: 50 Hz ON for 15 minutes

HIGH stimulation state example is, Current output: 3.0 milliAmps, Pulsewidth: 0.50 msec. Pulse frequency: 60 Hz ON for 30 minutes

These prepackaged/predetermined programs are nearly examples, and theactual stimulation parameters will deviate from these depending on thetreatment application.

It will be readily apparent to one skilled in the art, that otherschemes can be used for the same purpose. For example, instead ofplacing the magnet 90 on the pulse generator 171 for a prolonged periodof time, different stimulation states can be encoded by the sequence ofmagnet applications. Accordingly, in an alternative embodiment there canbe three logic states, OFF, LOW stimulation (LS) state, and HIGHstimulation (HS) state. Each logic state again corresponds to aprepackaged/predetermined program such as presented above. In such anembodiment, the system could be configured such that one application ofthe magnet triggers the generator into LS State. If the generator isalready in the LS state then one application triggers the device intoOFF State. Two successive magnet applications triggers the generatorinto MED stimulation state, and three successive magnet applicationstriggers the pulse generator in the HIGH Stimulation State.Subsequently, one application of the magnet while the device is in anystimulation state, triggers the device OFF.

FIG. 27 shows a representative digital circuitry used for the basicstate machine circuit. The circuit consists of a PROM 462 that has partof its data fed back as a state address. Other address lines 469 areused as circuit inputs, and the state machine changes its state addresson the basis of these inputs. The clock 104 is used to pass the newaddress to the PROM 462 and then pass the output from the PROM 462 tothe outputs and input state circuits. The two latches 464, 465 areoperated 180° out of phase to prevent glitches from unexpectedlyaffecting any output circuits when the ROM changes state. Each stateresponds differently according to the inputs it receives.

The advantage of this embodiment is that it is cheaper to manufacturethan a fully programmable implantable pulse generator (IPG).

Programmable Implantable Pulse Generator (IPG)

In one embodiment, a fully programmable implantable pulse generator(IPG) may be used. Shown in conjunction with FIG. 28, the implantablepulse generator unit 391 is preferably a microprocessor based device,where the entire circuitry is encased in a hermetically sealed titaniumcan. As shown in the overall block diagram, the logic & control unit 398provides the proper timing for the output circuitry 385 to generateelectrical pulses that are delivered to a pair of electrodes via a lead40. The pair of electrodes to which the stimulation energy is deliveredis switchable. Programming of the implantable pulse generator (I PG) isdone via an external programmer 85, as described later. Once programmedvia an external programmer 85, the implanted pulse generator 391provides appropriate electrical stimulation pulses to the nerve tissue54 via the stimulating electrode pair.

This embodiment may also comprise fixed pre-determined/pre-packagedprograms. Examples of LOW, LOW-MED, MED, and HIGH stimulation stateswere given in the previous section, under “Programmer-less ImplantablePulse Generator (IPG)”. These pre-packaged/pre-determined programscomprise unique combinations of pulse amplitude, pulse width, pulsefrequency, ON-time and OFF-time.

In addition, each parameter may be individually programmed and stored inmemory. A small library of “customized” programs that work particularlywell for the patient, may be programmed and stored in the implanteddevice. Any of the program can be activated on demand. The range ofprogrammable electrical stimulation parameters are shown in table 4below. TABLE 4 Programmable electrical parameter range PARAMER RANGEPulse Amplitude 0.1 Volt-10 Volts Pulse width 20 μS-5 mSec. Frequency 3Hz-300 Hz On-time 5 Secs-24 hours Ramp ON/OFF

Shown in conjunction with FIGS. 29 and 30, the electronic stimulationmodule comprises both digital 350 and analog 352 circuits. A main timinggenerator 330 (shown in FIG. 29), controls the timing of the analogoutput circuitry for delivering neuromodulating pulses to nerve tissue54, via output amplifier 334. Limiter 183 prevents excessive stimulationenergy from getting to the nerve tissue 54. The main timing generator330 receiving clock pulses from crystal oscillator 393. Main timinggenerator 330 also receiving input from programmer 85 via coil 399. FIG.30 highlights other portions of the digital system such as CPU 338, ROM337, RAM 339, program interface 346, interrogation interface 348, timers340, and digital O/l 342.

Most of the digital functional circuitry 350 is on a single chip (IC).This monolithic chip along with other IC's and components such ascapacitors and the input protection diodes are assembled together on ahybrid circuit. As well known in the art, hybrid technology is used toestablish the connections between the circuit and the other passivecomponents. The integrated circuit is hermetically encapsulated in achip carrier. A coil 399 situated under the hybrid substrate is used forbidirectional telemetry. The hybrid and battery 397 are encased in atitanium can 65. This housing is a two-part titanium capsule that ishermetically sealed by laser welding. Alternatively, electron-beamwelding can also be used. The header 79 is a cast epoxy-resin withhermetically sealed feed-through, and form the lead 40 connection block.

For further details, FIG. 31A highlights the general components of an8-bit microprocessor as an example. It will be obvious to one skilled inthe art that higher level microprocessor, such as a 16-bit or 32-bit maybe utilized, and is considered within the scope of this invention. Itcomprises a ROM 337 to store the instructions of the program to beexecuted and various programmable parameters, a RAM 339 to store thevarious intermediate parameters, timers 340 to track the elapsedintervals, a register file 321 to hold intermediate values, an ALU 320to perform the arithmetic calculation, and other auxiliary units thatenhance the performance of a microprocessor-based IPG system.

The size of ROM 337 and RAM 339 units are selected based on therequirements of the algorithms and the parameters to be stored. Thenumber of registers in the register file 321 are decided based upon thecomplexity of computation and the required number of intermediatevalues. Timers 340 of different precision are used to measure theelapsed intervals. Even though this embodiment does not have externalsensors to control timing, future embodiments may have sensors 322 toeffect the timing as shown in conjunction with FIG. 31B.

In this embodiment, the two main components of microprocessor are thedatapath and control. The datapath performs the arithmetic operation andthe control directs the datapath, memory, and I/O devices to execute theinstruction of the program. The hardware components of themicroprocessor are designed to execute a set of simple instructions. Ingeneral the complexity of the instruction set determines the complexityof datapth elements and controls of the microprocessor.

In this embodiment, the microprocessor is provided with a fixedoperating routine. Future embodiments may be provided with thecapability of actually introducing program changes in the implantedpulse generator. The instruction set of the microprocessor, the size ofthe register files, RAM 339 and ROM 337 are selected based on theperformance needed and the type of the algorithms used. In thisapplication of pulse generator, in which several algorithms can beloaded and modified, Reduced Instruction Set Computer (RISC)architecture is useful. RISC architecture offers advantages because itcan be optimized to reduce the instruction cycle which in turn reducesthe run time of the program and hence the current drain. The simpleinstruction set architecture of RISC and its simple hardware can be usedto implement any algorithm without much difficulty. Since size is also amajor consideration, an 8-bit microprocessor is used for the purpose. Asmost of the arithmetic calculation are based on a few parameters and arerather simple, an accumulator architecture is used to save bits fromspecifying registers. Each instruction is executed in multiple clockcycles, and the clock cycles are broadly classified into five stages: aninstruction fetch, instruction decode, execution, memory reference, andwrite back stages. Depending on the type of the instruction, all or someof these stages are executed for proper completion.

Initially, an optimal instruction set architecture is selected based onthe algorithm to be implemented and also taking into consideration thespecial needs of a microprocessor based implanted pulse generator (IPG).The instructions are broadly classified into Load/store instructions,Arithmetic and logic instructions (ALU), control instructions andspecial purpose instructions.

The instruction format is decided based upon the total number ofinstructions in the instruction set. The instructions fetched frommemory are 8 bits long in this example. Each instruction has an opcodefield (2 bits), a register specifier field (3-bits), and a 3-bitimmediate field. The opcode field indicates the type of the instructionthat was fetched. The register specifier indicates the address of theregister in the register file on which the operations are performed. Theimmediate field is shifted and sign extended to obtain the address ofthe memory location in load/store instruction. Similarly, in branch andjump instruction, the offset field is used to calculate the address ofthe memory location the control needs to be transferred to.

Shown in conjunction with FIG. 32A, the register file 321, which is acollection of registers in which any register can be read from orwritten to specifying the number of the register in the file. Based onthe requirements of the design, the size of the register file isdecided. For the purposes of implementation of stimulation pulsesalgorithms, a register file of eight registers is sufficient, with threespecial purpose register (0-2) and five general purpose registers (3-7),as shown in FIG. 32A. Register “0” always holds the value “zero”.Register “1” is dedicated to the pulse flags. Register “2” is anaccumulator in which all the arithmetic calculations are performed. Theread/write address port provides a 3-bit address to identify theregister being read or written into. The write data port provides 8-bitdata to be written into the registers either from ROM/RAM or timers.Read enable control, when asserted enables the register file to providedata at the read data port. Write enable control enables writing of databeing provided at the write data port into a register specified by theread/write address.

Generally, two or more timers are required to implement the algorithmfor the IPG 391. The timers are read and written into just as any othermemory location. The timers are provided with read and write enablecontrols.

The arithmetic logic unit 320 is an important component of themicroprocessor. It performs the arithmetic operation such as addition,subtraction and logical operations such as AND and OR. The instructionformat of ALU instructions consists of an opcode field (2 bits), afunction field (2 bits) to indicate the function that needs to beperformed, and a register specifier (3 bits) or an immediate field (4bits) to provide an operand.

The hardware components discussed above constitute the importantcomponents of a datapath. Shown in conjunction with FIG. 32B, there aresome special purpose registers such a program counter (PC) to hold theaddress of the instruction being fetched from ROM 337 and instructionregister (IR) 323, to hold the instruction that is fetched for furtherdecoding and execution. The program counter is incremented in eachinstruction fetch stage to fetch sequential instruction from memory. Inthe case of a branch or jump instruction, the PC multiplexer allows tochoose from the incremented PC value or the branch or jump addresscalculated. The opcode of the instruction fetched is provided to thecontrol unit to generate the appropriate sequence of control signals,enabling data flow through the datapath. The register specificationfield of the instruction is given as read/write address to the registerfile, which provides data from the specified field on the read dataport. One port of the ALU is always provided with the contents of theaccumulator and the other with the read data port. This design istherefore referred to as accumulator-based architecture. Thesign-extended offset is used for address calculation in branch and jumpinstructions. The timers are used to measure the elapsed interval andare enabled to count down on a low-frequency clock. The timers are readand written into, just as any other memory location (FIG. 32B).

In a multicycle implementation, each stage of instruction executiontakes one clock cycle. Since the datapath takes multiple clock cyclesper instruction, the control must specify the signals to be asserted ineach stage and also the next step in the sequence. This can be easilyimplemented as a finite state machine.

A finite state machine consists of a set of states and directions on howto change states. The directions are defined by a next-state function,which maps the current state and the inputs to a new state. Each stagealso indicates the control signals that need to be asserted. Every statein the finite state machine takes one clock cycle. Since the instructionfetch and decode stages are common to all the instruction, the initialtwo states are common to all the instruction. After the execution of thelast step, the finite state machine returns to the fetch state.

A finite state machine can be implemented with a register that holds thecurrent stage and a block of combinational logic such as a PLA. Itdetermines the datapath signals that need to be asserted as well as thenext state. A PLA is described as an array of AND gates followed by anarray of OR gates. Since any function can be computed in two levels oflogic, the two-level logic of PLA is used for generating controlsignals.

The occurrence of a wakeup event initiates a stored operating routinecorresponding to the event. In the time interval between a completedoperating routine and a next wake up event, the internal logiccomponents of the processor are deactivated and no energy is beingexpended in performing an operating routine.

A further reduction in the average operating current is obtained byproviding a plurality of counting rates to minimize the number of statechanges during counting cycles. Thus intervals which do not requiregreat precision, may be timed using relatively low counting rates, andintervals requiring relatively high precision, such as stimulating pulsewidth, may be timed using relatively high counting rates.

The logic and control unit 398 of the IPG controls the outputamplifiers. The pulses have predetermined energy (pulse amplitude andpulse width) and are delivered at a time determined by the therapystimulus controller. The circuitry in the output amplifier, shown inconjunction with (FIG. 33) generates an analog voltage or current thatrepresents the pulse amplitude. The stimulation controller moduleinitiates a stimulus pulse by closing a switch 208 that transmits theanalog voltage or current pulse to the nerve tissue through the tipelectrode 61 of the lead 40. The output circuit receiving instructionsfrom the stimulus therapy controller 398 that regulates the timing ofstimulus pulses and the amplitude and duration (pulse width) of thestimulus. The pulse amplitude generator 206 determines the configurationof charging and output capacitors necessary to generate the programmedstimulus amplitude. The output switch 208 is closed for a period of timethat is controlled by the pulse width generator 204. When the outputswitch 208 is closed, a stimulus is delivered to the tip electrode 61 ofthe lead 40.

The constant-voltage output amplifier applies a voltage pulse to thedistal electrode (cathode) 61 of the lead 40. A typical circuit diagramof a voltage output circuit is shown in FIG. 34. This configurationcontains a stimulus amplitude generator 206 for generating an analogvoltage. The analog voltage represents the stimulus amplitude and isstored on a holding capacitor C_(h) 225. Two switches are used todeliver the stimulus pulses to the lead 40, a stimulating deliveryswitch 220, and a recharge switch 222, that reestablishes the chargeequilibrium after the stimulating pulse has been delivered to the nervetissue. Since these switches have leakage currents that can cause directcurrent (DC) to flow into the lead system 40, a DC blocking capacitorC_(b) 229, is included. This is to prevent any possible corrosion thatmay result from the leakage of current in the lead 40. When the stimulusdelivery switch 220 is closed, the pulse amplitude analog voltage storedin the (Ch 225) holding capacitor is transferred to the cathodeelectrode 61 of the lead 40 through the coupling capacitor, C_(b) 229.At the end of the stimulus pulse, the stimulus delivery switch 220opens. The pulse duration being the interval from the closing of theswitch 220 to its reopening. During the stimulus delivery, some of thecharge stored on C_(h) 225 has been transferred to C_(b) 229, and somehas been delivered to the lead system 40 to stimulate the nerve tissue.

To re-establish equilibrium, the recharge switch 222 is closed, and arapid recharge pulse is delivered. This is intended to remove anyresidual charge remaining on the coupling capacitor C_(b) 229, and thestimulus electrodes on the lead (polarization). Thus, the stimulus isdelivered as the result of closing and opening of the stimulus delivery220 switch and the closing and opening of the RCHG switch 222. At thispoint, the charge on the holding C_(h) 225 must be replenished by thestimulus amplitude generator 206 before another stimulus pulse can bedelivered.

The pulse generating unit charges up a capacitor and the capacitor isdischarged when the control (timing) circuitry requires the delivery ofa pulse. This embodiment utilizes a constant voltage pulse generator,even though a constant current pulse generator can also be utilized.Pump-up capacitors are used to deliver pulses of larger magnitude thanthe potential of the batteries. The pump up capacitors are charged inparallel and discharged into the output capacitor in series. Shown inconjunction with FIG. 35 is a circuit diagram of a voltage doubler whichis shown here as an example. For higher multiples of battery voltage,this doubling circuit can be cascaded with other doubling circuits. Asshown in FIG. 35, during phase I (top of FIG. 35), the pump capacitorC_(p) is charged to V_(bat) and the output capacitor C_(o) suppliescharge to the load. During phase II, the pump capacitor charges theoutput capacitor, which is still supplying the load current. In thiscase, the voltage drop across the output capacitor is twice the batteryvoltage.

FIG. 36 shows an example of the pulse trains that are delivered withthis embodiment. The microcontroller is configured to deliver the pulsetrain as shown in the figure, i.e. there is “ramping up” of the pulsetrain. The purpose of the ramping-up is to avoid sudden changes instimulation, when the pulse train begins.

In one aspect of the invention, the electrical stimulation can besupplied uni-directionally and substantially blocked in the otherdirection, utilizing the “greenwave” effect. In such a case, as shown inconjunction with FIGS. 37 and 39, a tripolar lead is utilized. Asdepicted on the top right portion of FIG. 37, a depolarization peak 10on the nerve bundle corresponding to electrode 61 (cathode) and the twohyper-polarization peaks 8, 12 corresponding to electrodes 62, 63(anodes). With the microcontroller controlling the tripolar device, thesize and timing of the hyper-polarizations 8, 12 can be controlled. Asshown in conjunction with FIG. 38, since the speed of conduction isdifferent between the larger diameter A and B fibers and the smallerdiameter c-fibers, by appropriately timing the pulses, collision blockscan be created for conduction via the large diameter A and B fibers inthe afferent direction. This is depicted schematically in FIG. 39. Anumber of blocking techniques are known in the art, such as collisionblocking, high frequency blocking, and anodal blocking. Any of thesewell known blocking techniques may be used with the practice of thisinvention, and are considered within the scope of this invention.

The programming of the implanted pulse generator (IPG) 391 is shown inconjunction with FIGS. 40A and 40B. With the magnetic Reed Switch 389(FIGS. 28, 42) in the closed position, a coil in the head of theprogrammer 85, communicates with a telemetry coil 399 of the implantedpulse generator 391. Bi-directional inductive telemetry is used toexchange data with the implanted unit 391 by means of the externalprogramming unit 85.

The transmission of programming information involves manipulation of thecarrier signal in a manner that is recognizable by the pulse generator391 as a valid set of instructions. The process of modulation serves asa means of encoding the programming instruction in a language that isinterpretable by the implanted pulse generator 391. Modulation of signalamplitude, pulse width, and time between pulses are all used in theprogramming system, as will be appreciated by those skilled in the art.FIG. 41A shows an example of pulse count modulation, and FIG. 41B showsan example of pulse width modulation, that can be used for encoding.

FIG. 42 shows a simplified overall block diagram of the implanted pulsegenerator (IPG) 391 programming and telemetry interface. The left halfof FIG. 42 is programmer 85 which communicates programming and telemetryinformation with the IPG 391. The sections of the IPG 391 associatedwith programming and telemetry are shown on the right half of FIG. 42.In this case, the programming sequence is initiated by bringing apermanent magnet in the proximity of the IPG 391 which closes a reedswitch 389 in the IPG 391. Information is then encoded into a specialerror-correcting pulse sequence and transmitted electromagneticallythrough a set of coils. The received message is decoded, checked forerrors, and passed on to the unit's logic circuitry. The IPG 391 of thisembodiment includes the capability of bi-directional communication.

The reed switch 389 is a magnetically-sensitive mechanical switch, whichconsists of two thin strips of metal (the “reed”) which areferromagnetic. The reeds normally spring apart when no magnetic field ispresent. When a field is applied, the reeds come together to form aclosed circuit because doing so creates a path of least reluctance. Theprogramming head of the programmer contains a high-field-strengthceramic magnet.

When the switch closes, it activates the programming hardware, andinitiates an interrupt of the IPG central processor. Closing the reedswitch 389 also presents the logic used to encode and decode programmingand telemetry signals. A nonmaskable interrupt (NMI) is sent to the IPGprocessor, which then executes special programming software. Since theNMI is an edge-triggered signal and the reed switch is vulnerable tomechanical bounce, a debouncing circuit is used to avoid multipleinterrupts. The overall current consumption of the IPG increases duringprogramming because of the debouncing circuit and other communicationcircuits.

A coil 399 is used as an antenna for both reception and transmission.Another set of coils 383 is placed in the programming head, a relativelysmall sized unit connected to the programmer 85. All coils are tuned tothe same resonant frequency. The interface is half-duplex with one unittransmitting at a time.

Since the relative positions of the programming head 87 and IPG 391determine the coupling of the coils, this embodiment utilizes a specialcircuit which has been devised to aid the positioning of the programminghead, and is shown in FIG. 43. It operates on similar principles to thelinear variable differential transformer. An oscillator tuned to theresonant frequency of the pacemaker coil 399 drives the center coil of athree-coil set in the programmer head. The phase difference between theoriginal oscillator signal and the resulting signal from the two outercoils is measured using a phase shift detector. It is proportional tothe distance between the implanted pulse generator and the programmerhead. The phase shift, as a voltage, is compared to a reference voltageand is then used to control an indicator such as an LED. An enablesignal allows switching the circuit on and off.

Actual programming is shown in conjunction with FIGS. 44 and 45.Programming and telemetry messages comprise many bits; however, the coilinterface can only transmit one bit at a time. In addition, the signalis modulated to the resonant frequency of the coils, and must betransmitted in a relatively short period of time, and must providedetection of erroneous data.

A programming message is comprised of five parts FIG. 44(a). The startbit indicates the beginning of the message and is used to synchronizethe timing of the rest of the message. The parameter number specifieswhich parameter (e.g., mode, pulse width, delay) is to be programmed. Inthe example, in FIG. 44(a) the number 10010000 specifies the pulse rateto be specified. The parameter value represents the value that theparameter should be set to. This value may be an index into a table ofpossible values; for example, the value 00101100 represents a pulsestimulus rate of 80 pulses/min. The access code is a fixed number basedon the stimulus generator model which must be matched exactly for themessage to succeed. It acts as a security mechanism against use of thewrong programmer, errors in the message, or spurious programming fromenvironmental noise. It can also potentially allow more than oneprogrammable implant in the patient. Finally, the parity field is thebitwise exclusive-OR of the parameter number and value fields. It is oneof several error-detection mechanisms.

All of the bits are then encoded as a sequence of pulses of 0.35-msduration FIG. 44(b). The start bit is a single pulse. The remaining bitsare delayed from their previous bit according to their bit value. If thebit is a zero, the delay is short (1.0); if it is a one, the delay islong (2.2 ms). This technique of pulse position coding, makes detectionof errors easier.

The serial pulse sequence is then amplitude modulated for transmissionFIG. 44(c). The carrier frequency is the resonant frequency of thecoils. This signal is transmitted from one set of coils to the other andthen demodulated back into a pulse sequence FIG. 44(d).

FIG. 45 shows how each bit of the pulse sequence is decoded from thedemodulated signal. As soon as each bit is received, a timer beginstiming the delay to the next pulse. If the pulse occurs within aspecific early interval, it is counted as a zero bit (FIG. 45(b)). If itotherwise occurs with a later interval, it is considered to be a one bit(FIG. 45(d)). Pulses that come too early, too late, or between the twointervals are considered to be errors and the entire message isdiscarded (FIG. 45(a, c, e)). Each bit begins the timing of the bit thatfollows it. The start bit is used only to time the first bit.

Telemetry data may be either analog or digital. Digital signals arefirst converted into a serial bit stream using an encoding such as shownin FIG. 45(b). The serial stream or the analog data is then frequencymodulated for transmission.

An advantage of this and other encodings is that they provide multipleforms of error detection. The coils and receiver circuitry are tuned tothe modulation frequency, eliminating noise at other frequencies.Pulse-position coding can detect errors by accepting pulses only withinnarrowly-intervals. The access code acts as a security key to preventprogramming by spurious noise or other equipment. Finally, the parityfield and other checksums provides a final verification that the messageis valid. At any time, if an error is detected, the entire message isdiscarded.

Another more sophisticated type of pulse position modulation may be usedto increase the bit transmission rate. In this, the position of a pulsewithin a frame is encoded into one of a finite number of values, e.g.16. A special synchronizing bit is transmitted to signal the start ofthe frame. Typically, the frame contains a code which specifies the typeor data contained in the remainder of the frame.

FIG. 46 shows a diagram of receiving and decoding circuitry forprogramming data. The IPG coil, in parallel with capacitor creates atuned circuit for receiving data. The signal is band-pass filtered 602and envelope detected 604 to create the pulsed signal in FIG. 44(d).After decoding, the parameter value is placed in a RAM at the locationspecified by the parameter number. The IPG can have two copies of theRAM—a permanent set and a temporary set—which makes it easy for thephysician to set the IPG to a temporary configuration and laterreprogram it back to the usual settings.

FIG. 47 shows the basic circuit used to receive telemetry data. Again, acoil and capacitor create a resonant circuit tuned to the carrierfrequency. The signal is further band-pass filtered 614 and thenfrequency-demodulated using a phase-locked loop 618.

This embodiment also comprises an optional battery status test circuit.Shown in conjunction with FIG. 48, the charge delivered by the batteryis estimated by keeping track of the number of pulses delivered by theIPG 391. An internal charge counter is updated during each test mode toread the total charge delivered. This information about battery statusis read from the IPG 391 via telemetry.

Combination Implantable Device Comprising both a Stimulus-Receiver and aProgrammable Implantable Pulse Generator (IPG)

In one embodiment, the implantable device may comprise both astimulus-receiver and a programmable implantable pulse generator (IPG).FIG. 49 shows a close up view of the packaging of the implantedstimulator 75 of this embodiment, showing the two subassemblies 120, 70.The two subassemblies are the stimulus-receiver module 120 and thebattery operated pulse generator module 70. The external stimulator 42,and programmer 85 also being remotely controllable from a distantlocation via the internet. Controlling circuitry means within thestimulator 75, makes the inductively coupled stimulator 120 and the IPG70 operate in harmony with each other. For example, when stimulation isapplied via the inductively coupled system, the battery operated portionof the stimulator is triggered to go into the “sleep” mode. Conversely,when programming pulses (which are also inductively coupled) are beingapplied to the implanted battery operated pulse generator 70, theinductively coupled stimulation circuitry 120 is disconnected.

FIG. 52A is a simplified diagram of one aspect of control circuitry. Inthis embodiment, to program the implanted portion of the stimulator 70,a magnet 144 is placed over the implanted pulse generator 70, causing amagnetically controlled Reed Switch 182 (which is normally in the openposition) to be closed. As is also shown in FIG. 52A, at the same time aswitch 67 going to the stimulator lead 40, and a switch 69 going to thecircuit of the stimulus-receiver module 120 are both opened,disconnecting both subassemblies electrically. Further, protectioncircuitry 181 is an additional safeguard for inadvertent leakage ofelectrical energy into the nerve tissue 54 during programming.Alternatively, as shown in FIG. 52B, instead of a reed switch 182, asolid state magnet sensor (Hall-effect sensor) 146 may be used for thesame purpose. The solid-state magnet sensor 146 is preferred, sincethere are no moving parts that can get stuck.

With reference to FIG. 50, for the functioning of the inductivelycoupled stimulus-receiver 120, a primary (external) coil 46 is placed inclose proximity to secondary (implanted) coil 48. The primary coil 46may be taped to skin 60, or other means may be used for keeping theprimary coil 46 in close proximity to the implanted (secondary) coil 48.Referring to the left portion of FIG. 50, the amplitude and pulse widthmodulated radiofrequency signals from the primary (external) coil 46 areinductively coupled to the secondary (implanted) coil 48 in theimplanted unit 75. The two coils 46 and 48 thus act like an air-gaptransformer. The system having means for proximity sensing between thetwo coils 46,48, and feedback regulation of signals as describedearlier.

Again with reference to FIG. 50, the combination of capacitor 122 andinductor 48 tunes the receiver circuitry to the high frequency of thetransmitter with the capacitor 122. The receiver is made sensitive tofrequencies near the resonant frequency of the tuned circuit, and lesssensitive to frequencies away from the resonant frequency. A diodebridge 124 rectifies the alternating voltages. Capacitor 128 andresistor 134 filter out the high-frequency component of the receiversignal, and leaves the current pulse of the same duration as the burstsof the high-frequency signal. A zenor diode 139 is used for regulationand capacitor 136 blocks any net direct current.

As shown in conjunction with FIGS. 50 and 51A the pulses generated fromthe stimulus-receiver circuitry 120 are compared to a reference voltage,which is programmed in the implanted pulse generator 70. When thevoltage of incoming pulses exceeds the reference voltage (FIG. 51B), theoutput of the comparator 178,180 sends digital pulse 89 (shown in FIG.51C) to the stimulation electric module 184. At this predeterminedlevel, the high threshold comparator 178 fires and the controller 184suspends any stimulation from the implanted pulse generator 70. Theimplanted pulse generator 70 goes into “sleep” mode for a predeterminedperiod of time. In one preferred embodiment, the level of voltage neededfor the battery operated stimulator to go into “sleep” mode is aprogrammable parameter. The length of time, the implanted pulsegenerator 70 remains in “sleep” mode is also a programmable parameter.Therefore, advantageously the external stimulator 42 in conjunction withthe inductively coupled part of the stimulator 120 can be used to savethe battery life of the implanted stimulator 75.

In one embodiment, the external stimulator 42 is networked using theinternet, giving the attending physician full control for activating andde-activating selected programs. Using “trial and error” variousprograms for electrical pulse therapy can be custom adjusted for thephysiology of the individual patent. Also, by using the externalstimulator 42, the battery 188 of the implanted stimulator unit 75 canbe greatly extended. Further, even after the battery 188 is depleted,the system can still be used for neuromodulation using thestimulus-receiver module 120, and the external stimulator 42.

FIG. 53 shows a diagram of the finished implantable stimulator 75. FIG.54 shows the pulse generator with some of the components used inassembly in an exploded view. These components include a coil cover 7,the secondary coil 48 and associated components, a magnetic shield 9,and a coil assembly carrier 11. The coil assembly carrier 11 has atleast one positioning detail 13 located between the coil assembly andthe feed through for positioning the electrical connection. Thepositioning detail 13 secures the electrical connection.

Implantable Pulse Generator (IPG) Comprising a Rechargeable Battery

In one embodiment, an implantable pulse generator with rechargeablepower source can be used. In such an embodiment (shown in conjunctionwith FIG. 55), a recharge coil is external to the pulse generatortitanium can. The RF pulses transmitted via coil 46 and received viasubcutaneous coil 48A are rectified via diode bridge 154. These DCpulses are processed and the resulting current applied to recharge thebattery 188A in the implanted pulse generator.

In summary, in the of current invention for providing pulse electricalstimulation to one of sacral plexus or branches, inferior hypogastricplexus or branches, superior hypogastric plexus or branches in apatient, to provide therapy for one of erectile/sexual dysfunction,prostatitis, pelvic pain, pain originating from prostatitis pathology,can be practiced with any of the several power sources disclosedincluding,

-   -   a) an implanted stimulus-receiver with an external stimulator;    -   b) an implanted stimulus-receiver comprising a high value        capacitor for storing charge, used in conjunction with an        external stimulator;    -   c) a programmer-less implantable pulse generator (I PG) which is        operable with a magnet;    -   d) a programmable implantable pulse generator;    -   e) a combination implantable device comprising both a        stimulus-receiver and a programmable IPG; and    -   f) an IPG comprising a rechargeable battery.

Neuromodulation of the appropriate nerve tissue(s) with any of thesesystems is considered within the scope of this invention.

In one embodiment, the external stimulator and/or the programmer has atelecommunications module, as described in a co-pending application, andsummarized here for reader convenience. The telecommunications modulehas two-way communications capabilities.

FIGS. 56 and 57 depict communication between an external stimulator 42and a remote hand-held computer 502. A desktop or laptop computer can bea server 500 which is situated remotely, perhaps at a physician's officeor a hospital. The stimulation parameter data can be viewed at thisfacility or reviewed remotely by medical personnel on a hand-heldpersonal data assistant (PDA) 502, such as a “palm-pilot” from PALMcorp. (Santa Clara, Calif.), a “Visor” from Handspring Corp. (Mountainview, Calif.) or on a personal computer (PC). The physician orappropriate medical personnel, is able to interrogate the externalstimulator 42 device and know what the device is currently programmedto, as well as, get a graphical display of the pulse train. The wirelesscommunication with the remote server 500 and hand-held PDA 502 would besupported in all geographical locations within and outside the UnitedStates (US) that provides cell phone voice and data communicationservice.

In one aspect of the invention, the telecommunications component can useWireless Application Protocol (WAP). The Wireless Application Protocol(WAP), which is a set of communication protocols standardizing Internetaccess for wireless devices. While previously, manufacturers useddifferent technologies to get Internet on hand-held devices, with WAPdevices and services interoperate. WAP also promotes convergence ofwireless data and the Internet. The WAP programming model is heavilybased on the existing Internet programming model, and is shownschematically in FIG. 58. Introducing a gateway function provides amechanism for optimizing and extending this model to match thecharacteristics of the wireless environment. Over-the-air traffic isminimized by binary encoding/decoding of Web pages and readapting theInternet Protocol stack to accommodate the unique characteristics of awireless medium such as call drops.

The key components of the WAP technology, as shown in FIG. 58,includes 1) Wireless Mark-up Language (WML) 550 which incorporates theconcept of cards and decks, where a card is a single unit of interactionwith the user. A service constitutes a number of cards collected in adeck. A card can be displayed on a small screen. WML supported Web pagesreside on traditional Web servers. 2) WML Script which is a scriptinglanguage, enables application modules or applets to be dynamicallytransmitted to the client device and allows the user interaction withthese applets. 3) Microbrowser, which is a lightweight applicationresident on the wireless terminal that controls the user interface andinterprets the WMLA/MLScript content. 4) A lightweight protocol stack520 which minimizes bandwidth requirements, guaranteeing that a broadrange of wireless networks can run WAP applications. The protocol stackof WAP can comprise a set of protocols for the transport (WTP), session(WSP), and security (WTLS) layers. WSP is binary encoded and able tosupport header caching, thereby economizing on bandwidth requirements.WSP also compensates for high latency by allowing requests and responsesto be handled asynchronously, sending before receiving the response toan earlier request. For lost data segments, perhaps due to fading orlack of coverage, WTP only retransmits lost segments using selectiveretransmission, thereby compensating for a less stable connection inwireless. The above mentioned features are industry standards adoptedfor wireless applications and greater details have been publicized, andwell known to those skilled in the art.

In this embodiment, two modes of communication are possible. In thefirst, the server initiates an upload of the actual parameters beingapplied to the patient, receives these from the stimulator, and storesthese in its memory, accessible to the authorized user as a dedicatedcontent driven web page. The physician or authorized user can makealterations to the actual parameters, as available on the server, andthen initiate a communication session with the stimulator device todownload these parameters.

Shown in conjunction with FIG. 59, in one embodiment, the externalstimulator 42 and/or the programmer 85 may also be networked to acentral collaboration computer 286 as well as other devices such as aremote computer 294, PDA 502, phone 141, physician computer 143. Theinterface unit 292 in this embodiment communicates with the centralcollaborative network 290 via land-lines such as cable modem orwirelessly via the internet. A central computer 286 which has sufficientcomputing power and storage capability to collect and process largeamounts of data, contains information regarding device history andserial number, and is in communication with the network 290.Communication over collaboration network 290 may be effected by way of aTCP/IP connection, particularly one using the internet, as well as aPSTN, DSL, cable modem, LAN, WAN or a direct dial-up connection.

The standard components of interface unit shown in block 292 areprocessor 305, storage 310, memory 308, transmitter/receiver 306, and acommunication device such as network interface card or modem 312. In thepreferred embodiment these components are embedded in the externalstimulator 42 and can also be embedded in the programmer 85. These canbe connected to the network 290 through appropriate security measures(Firewall) 293.

Another type of remote unit that may be accessed via centralcollaborative network 290 is remote computer 294. This remote computer294 may be used by an appropriate attending physician to instruct orinteract with interface unit 292, for example, instructing interfaceunit 292 to send instruction downloaded from central computer 286 toremote implanted unit.

Shown in conjunction with FIGS. 60A and 60B the physician's remotecommunication's module is a Modified PDA/Phone 502 in this embodiment.The Modified PDA/Phone 502 is a microprocessor based device as shown ina simplified block diagram in FIGS. 65A and 65B. The PDA/Phone 502 isconfigured to accept PCM/CIA cards specially configured to fulfill therole of communication module 292 of the present invention. The ModifiedPDA/Phone 502 may operate under any of the useful software includingMicrosoft Window's based, Linux, Palm OS, Java OS, SYMBIAN, or the like.

The telemetry module 362 comprises an RF telemetry antenna 142 coupledto a telemetry transceiver and antenna driver circuit board whichincludes a telemetry transmitter and telemetry receiver. The telemetrytransmitter and receiver are coupled to control circuitry and registers,operated under the control of microprocessor 364. Similarly, withinstimulator a telemetry antenna 142 is coupled to a telemetry transceivercomprising RF telemetry transmitter and receiver circuit. This circuitis coupled to control circuitry and registers operated under the controlof microcomputer circuit.

With reference to the telecommunications aspects of the invention, thecommunication and data exchange between Modified PDA/Phone 502 andexternal stimulator 42 operates on commercially available frequencybands. The 2.4-to-2.4853 GHz bands or 5.15 and 5.825 GHz, are the twounlicensed areas of the spectrum, and set aside for industrial,scientific, and medical (ISM) uses. Most of the technology todayincluding this invention, use either the 2.4 or 5 GHz radio bands andspread-spectrum technology.

The telecommunications technology, especially the wireless internettechnology, which this invention utilizes in one embodiment, isconstantly improving and evolving at a rapid pace, due to advances in RFand chip technology as well as software development. Therefore, one ofthe intents of this invention is to utilize “state of the art”technology available for data communication between Modified PDA/Phone502 and external stimulator 42. The intent of this invention is to use3G technology for wireless communication and data exchange, even thoughin some cases 2.5G is being used currently.

For the system of the current invention, the use of any of the “3G”technologies for communication for the Modified PDA/Phone 502, isconsidered within the scope of the invention. Further, it will beevident to one of ordinary skill in the art that as future 4G systems,which will include new technologies such as improved modulation andsmart antennas, can be easily incorporated into the system and method ofcurrent invention, and are also considered within the scope of theinvention.

1. A method of providing pulsed electrical stimulation to at least oneof sacral plexus, inferior hypogastric plexus, and superior hypogastricplexus or their branches or portion thereof, for treating or alleviatingthe symptoms for at least one of erectile/sexual dysfunction,prostatitis, pelvic pain, pain originating from prostatitis pathology,comprising the steps of: a) providing a microprocessor based pulsegenerator to supply electrical pulses; wherein said pulse generatorconsists of one from a group comprising of: an implantedstimulus-receiver with an external stimulator; an implantedstimulus-receiver comprising a high value capacitor for storing charge,used in conjunction with an external stimulator; a programmer-lessimplantable pulse generator (IPG) which is operable with a magnet; aprogrammable implantable pulse generator; a combination implantabledevice comprising both a stimulus-receiver and a programmable IPG; andan IPG comprising a rechargeable battery: b) providing at least onepredetermined program to control the output of said pulse generator; c)providing a lead in electrical contact with said pulse generator; d)activating said at least one predetermined program to emit saidelectrical pulses to at least one said plexuses or their branches orportion thereof; and e) providing at least one electrode connected tosaid lead; wherein said at least one electrode is adapted to be incontact with at least one of said plexuses or their branches or portionthereof, to provide said pulsed electrical pulses for said disorders. 2.A method of claim 1, wherein said plexuses or their branches or portionthereof in a patient further comprises, at least one of the pudendalnerve or its branches or portion thereof, the cavernous nerve or itsbranches or portion thereof, the prostatic plexus nerve or its branchesor portion thereof, the sacral splanchnic nerve or its branches orportion thereof, or pelvic splanchnic nerve or its branches or portionthereof, or sacral nerves S1, S2, S3, or S4.
 3. A method of claim 1,wherein said pulse generator further comprises telemetry means toremotely interrogate said pulse generator.
 4. A method of claim 1,wherein said pulse generator further comprises telemetry means toremotely control said electrical pulses.
 5. A method of claim 1, whereinsaid electrical pulses are provided to said nerves for unidirectionalstimulation.
 6. A method of claim 1, wherein said electrical pulses areprovided at any point along the length of said plexuses or theirbranches or portion thereof.
 7. A method of claim 1, wherein saidpredetermined program(s) comprises: a) at least one variable componentselected from a group comprising of pulse amplitude, pulse width, pulsefrequency, ON-time, and OFF-time; and b) controls said variablecomponent of said electric pulses.
 8. A method of claim 1, wherein saidpredetermined program(s) can be modified.
 9. A method for treating oralleviating the symptoms for at least one of erectile/sexualdysfunction, prostatitis, pelvic pain, and pain originating fromprostatitis pathology, with neuromodulation therapy, comprising thesteps of: a) selecting a patient for said neuromodulation therapy; b)providing a pulse generator system, wherein said pulse generator systemcomprises implantable and external components, and wherein said pulsegenerator system further comprises a microprocessor based circuitry; c)providing programming means to program said pulses generated by saidpulse generator; d) providing telemetry means for remote 2-waycommunication with said pulse generator over a wide area network; and e)providing at least one electrode in electrical contact with said pulsegenerator and adapted to be in contact with at least one of the sacralplexus or branches, inferior hypogastric plexus or branches, superiorhypogastric plexus or branches in a patient to provide saidneuromodulation therapy.
 10. The method of claim 9, wherein said pulsegenerator consists of one from a group comprising of: an implantedstimulus-receiver with an external stimulator; an implantedstimulus-receiver comprising a high value capacitor for storing charge,used in conjunction with an external stimulator; a programmer-lessimplantable pulse generator (IPG) which is operable with a magnet; aprogrammable implantable pulse generator; a combination implantabledevice comprising both a stimulus-receiver and a programmable IPG; andan IPG comprising a rechargeable battery.
 11. A method of claim 9,wherein said plexuses or their branches or portion thereof in a patientfurther comprises, at least one of pudendal nerve or its branches orportion thereof, cavernous nerve or its branches or portion thereof,prostatic plexus nerve or its branches or portion thereof, sacralsplanchnic nerve or its branches or portion thereof, or pelvicsplanchnic nerve or its branches or portion thereof, or sacral nervesS1, S2, S3, or S4.
 12. A method of claim 9, wherein said electricalpulses are provided for unidirectional neuromodulation therapy.
 13. Amethod of claim 9, wherein said electrical pulses are provided at anypoint along the length of said plexuses or their branches or portionthereof.
 14. A system of providing pulsed electrical stimulation to atleast one of sacral plexus, inferior hypogastric plexus, supereiorhypogastric plexus or their branches or portion thereof in a patient,for treating or alleviating the symptoms for at least one oferectile/sexual dysfunction, prostatitis, pelvic pain, and painoriginating from prostatitis pathology, comprising: a) a microprocessorbased pulse generator; wherein said pulse generator comprises at leastone predetermined program to deliver said electrical pulses; b) meansfor programming said pulse generator; and c) a lead in electricalcontact with said pulse generator; wherein said lead comprising at leastone electrode adapted to be in contact with at least one of saidplexuses or their branches or portion thereof in a patient; d) telemetrymeans for remote two way communication with said pulse generator over awide area network.
 15. A system of claim 14, wherein said plexuses ortheir branches or portion thereof in a patient further comprises, atleast one of pudendal nerve or its branches or portion thereof,cavernous nerve or its branches or portion thereof, prostatic plexus orits branches or portion thereof, sacral splanchnic nerve or its branchesor portion thereof, or pelvic splanchnic nerve or its branches orportion thereof, or sacral nerves S1, S2, S3, or S4.
 16. A system ofclaim 14, wherein said pulse generator consists of one from a groupcomprising of: an implanted stimulus-receiver with an externalstimulator; an implanted stimulus-receiver comprising a high valuecapacitor for storing charge, used in conjunction with an externalstimulator; a programmer-less implantable pulse generator (I PG) whichis operable with a magnet; a programmable implantable pulse generator; acombination implantable device comprising both a stimulus-receiver and aprogrammable IPG; and an IPG comprising a rechargeable battery.
 17. Asystem of claim 14, wherein said telemetry means is further utilized toremotely said electrical pulses and interrogation of said pulsegenerator.
 18. A system of claim 14, wherein said electrical pulses areprovided for unidirectional stimulation.
 19. A system of claim 14,wherein said electrical pulses are provided at any point along thelength of at least one of said plexuses or their branches or portionthereof.
 20. A system of claim 14, wherein said predetermined program(s)comprises: a) at least one variable component selected from a groupcomprising consisting of pulse amplitude, pulse width, pulse frequency,ON-time, and OFF-time; and b) controls said variable component of saidelectric pulses.
 21. A system of claim 14, wherein said predeterminedprogram(s) can be modified.
 22. The system of claim 14, wherein saidlead comprises a lead body with insulation selected from the groupconsisting of polyurethane, silicone and silicone withpolytetrafluoroethylene.
 23. The system of claim 14, wherein said atleast one electrode consists from a group comprising, spiral electrodes,cuff electrodes, steroid eluting electrodes, wrap-around electrodes, andhydrogel electrodes.
 24. The system of claim 23, wherein said electrodesare made from material from one of a group comprising of pure platinum,platinum-iridium alloy, platinum-iridium coated with titanium nitride,or carbon.